EX­PLO­SIVE STRESS RE­AC­TION

BBC Wildlife Magazine - - Wild December -

For most an­i­mals, stress is a turn-off – but not for male spot­ted sala­man­ders.

The dot­ted am­phib­ians are ex­plo­sive breed­ers, gath­er­ing to­gether en masse for a brief pe­riod dur­ing which males de­posit pack­ages of sperm for col­lec­tion by fe­males.

New re­search shows that males re­spond to dan­ger – in this case, hu­man han­dling – by de­posit­ing more sperm when they next meet a fe­male.

While other an­i­mals would post­pone re­pro­duc­tion un­til the threat has passed, sala­man­ders have evolved to con­sider they may not get an­other chance – and should go out with a bang. The club-like claws of the man­tis shrimp are great for smash­ing open crabs, but some­thing of a li­a­bil­ity in con­tests with ri­vals. Lit­tle sur­prise, then, that they pre­fer al­ter­na­tive meth­ods.

In the Cen­tral Amer­i­can species Neogon­odacty­lus bre­dini males at­tempt to set­tle con­tests quickly and blood­lessly, dis­play­ing their open claws to in­tim­i­date com­peti­tors. This doesn’t work, though, when the op­po­nents are sim­i­lar sizes. In that case, they es­ca­late to spar­ring, ab­sorb­ing blows with their tail-plates. The win­ner is the one who can de­liver the most strikes, rather than the hard­est.

If they are still evenly matched, things get grisly. Ac­cord­ing to Pa­trick Green of Duke Univer­sity, Durham, North Carolina, their clubs aren’t their only weapons: “When con­tests es­ca­lated past spar­ring, we saw com­peti­tors un­fold part of their claw and use it to spear each other.” The two terms are of­ten used in­ter­change­ably to de­scribe an or­gan­ism that de­ploys tox­ins for the pur­poses of at­tack or de­fence. Bi­o­log­i­cally, though, they have spe­cific mean­ings. Ven­omous species such as jel­ly­fish, black wid­ows and adders ac­tively de­liver their chem­i­cal arse­nal into their vic­tim with a bite or sting. But poi­sonous ones – for ex­am­ple lady­birds, poi­sonar­row frogs and yew berries – are more pas­sive, and only un­leash their tox­ins when nib­bled or touched. How­ever, eat a ven­omous an­i­mal and you could find it proves to be poi­sonous, too.

Adders are ven­omous as they de­liver toxin through a bite.

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